Study And Implementation Of File Search System On Unstructured P2P Network

In a P2P file-sharing system, the end client exchange files in the Internet. File searching and file delivery are two crucial problems need to be solved in P2P system. The nature of distributed storage of P2P makes it easier to implement a scalable system of file delivery. The difficulty is how to locate the peer who has the target file, and it is also the problem this thesis to solve.Firstly, this thesis introduces the technique of P2P network and the P2P file-sharing system, studies the file search in P2P file-sharing system. Then, on the basis of analyzing the architecture of P2P network and the file search algorithm, we study the DiffSearch algorithm, an improved algorithm based on the Flooding on unstructured P2P network. This algorithm identifies the peers based on the number of effective shared files, setting them as Peer or UltraPeer. Peers can find the information of Ultrapeers through messages of searching in the network, and compose an overlay with Ultrapeers connected with each other. Most of searches can be finished in the overlay. The DiffSearch algorithm is set to be the main algorithm of the file search system in this thesis. Then the system is designed to finish file search. Based on functions of file search system, it is divided into four models, each of which implements start, termination, searching and system setting. The function of two-round search is implemented in the search model elaborately. Further, coding of the system is implemented with Java on the platform of JXTA in order to buildup the system through the DiffSearch algorithm. Finally, a test is executed on the system which provides a query and makes a response to show the information of relating files to prove the effective of the system.